Effects of additional Ag on the thermal stability and glass-forming ability of La–Al–Cu bulk glassy alloys

The addition of Ag to La–Al–Cu ternary glassy alloys greatly increases the stabilization of supercooled liquid and glass-forming ability (GFA). The large supercooled liquid region (ΔTx) exceeding 60 K was obtained in a wide composition range of 10–22.5 at.% Al, 15–25 at.% Cu, and 2–12.5 at.% Ag. The largest ΔTx of 83 K and the reduced glass transition temperature (Tg/Tl) were obtained for La62.5Al12.5Ag5Cu20 alloy, leading to formation of the glassy alloy sample with a diameter of 6.0 mm. The addition of small amounts of Fe or Co to La–Al–Ag–Cu alloy increases Tg/Tl though the decrease in Tl, resulting in an increase of GFA. As a result, the glassy alloy rods with diameters of over 7.0 mm were fabricated by addition of 2.5–5 at.% Fe or Co. The new La-based bulk glassy alloys exhibited high compressive fracture strength of 589–858 MPa with distinct plastic strain of 0.2–1.0%.